sjspeck:Skiers do it all the time. And I don't think the airlines even charge extra for it. Or at least they didn't use to.
What you really need to devise is some sort of universal housing mount with an adjustable clamp on one end. Then borrow a pole/gaff from the boat to clamp it to. Just deal with the up/down motion as best as you can. Saves carrying a pole...
I did see a video housing somewhere that had a port for a coax cable so you could feed the images remotely back to a video monitor on the boat. Maybe an armored cable version would work. Otherwise how would you know what you're filming. Of course if a Great White takes a liking to your housing, I'm guessing it's pretty much a write-off anyway.
I guess you could also try something like this: (maybe only once if you're chumming in the area - LOL) http://www.aquavu.com/av_spoolsc100.html
I don't know how you'd trigger a still camera either, R/F signals probably wouldn't penetrate the water. What about a really long cable release? I wonder if you could use a piece of braided steel rubber house (like the stuff used on h/p car engines) as an outer protectant and run the cable down through the center to a gland in the camera housing. Your end wouldn't have to be sealed if you could keep it out of the water. You can buy the glands from Ikelite.
Later Edit: I just happened to see cables/glands and a pole mount on the Equinox website:
http://www.underwatervideohousings.com/misc.shtml
I really love the little camera fish...I am sure it wont last long in Gansbay though! Some folks have put one of those mini wireless cameras in a surfboard and then towed it to film a great white attack...Man, you should've seen them teethmarks on the board!
All in all, specifically for great whites and gansbay conditions, it is probably better a fixed pole. Viz is generally not that great and you would want to keep the camera about 2 feet from the snout as the sharks comes in for for the chum. I do not think one would have the time to even peak in a remote monitor. Someone else will be yanking the rope bringing the chum close to the boat. You shouldn't let the sharks have the bait, otherwise they may associate food with people.....Bad Kharma!
Crocs and Hippos are other instances where a pole would be handy...
Regretfully, in EU we have 20 Kilos (about 50 lbs) luggage allowance....Essentially my diving gear so I have to be mindful of what I pack or rent some of the gear - something I don't usually like to do in third world countries -
On the plus side, I've got over 200K air miles so it looks like a trip to the South Pacific is getting really close....If I can ever manage to take a whole month off!
I was in Maui this past November but I was not impressed. Except for turtles, there isn't much fish left and there are no Tiger sharks dives. Bummer, I will have to go back to S. Africa for the Tigers...They are actually a lot more inquisitive than the great whites and will come to give you a close up look. Also, it seems to me that dive operators in the US are afraid of liability and keep the dives really LAME but perhaps I just have not found a good one.......